Combined voltmeter and phase-rotation indicator



Sept. 6, 1927. 1,641,757

H. w. HALL COMBINED VOLT METER AND PHASE ROTATION INDICATOR Filed Ma 26. 1924 |n\ /c-ant;or- Hor'ton W Hall,

His Atc, oY-r ey.

Patented Sept. 6, 1927. V i v I i entree; STAT-ES eras-f HORTON 'w. HALL, OF LYNN, MASSACHUSETTS; ASSIGNOR; To" GENERAL ELECTRIC COMPANY, A CORPORATION OFNEW YORK. COMBINED VOLTME'IER AND PHASEROTATION INDICATOR. I

Application filed May as, 1924. se iai- No. 715,787.,

My invention e ates o a com n vo t For a better under n ing t-Iny in enmeter and phase rotationindicator for altertion reference ig' mad in th fou in d nating current circui s nd its bje t'is to c pt on to the ac mpanying draw ng in provide a simple device to be used in conwhich Fig. 1 represents the circuit conne nection with the usual double scale altertions involved in my inventionyFig. 2 rep- Hating current vo tmeter so hat the volt res n s th ex ernal. appea ance of the auxilmeter may be used to indicate the phase .rolary reactance used with my inventiomFig. 55 tation of a p yph cui 3 represents a schematic diag am of the cire s d doub e-scale voltmeter h Q it co nect ons when he instrum nt is sed 19 three terminals, one terminal being common for indicating phase. rotation; and Figs. 1 and the other two terminals being .used and-5 are ve t r dia ex a of alternately for ditlerent voltages for indi clockwise and counter-clockwiee phase rota- BU eating voltages from Zero to 150, the volt tlon indications respectively. Y 1 meter coils may be connected to the circuit Referring now, to Fig.1, represents th by one setof terminals so that a full scale caslng of an ordinary doublescale alternat deflection corresponds to 150 volts and for ing current volt Ineterwith the] covering indicating. higher voltages the- Volt; meter removed in order to show the interior par-ts. as coils may be connected in series with" a The scaleis indicated t 11, th ointe t permanent resistance which is generally 12, thecoils atV and the internal resistance mounted in the volt me case so tha ul t R- Tlie ins ruments represented as b scale deflection corresponds to 300' volts. ing. of thefdynamometer typehaving sta- Hy invention consists inv adding to'such a tionary and-movable coils connected in" v lt meter a suitable reactance ,coil or other ries. \Vhenthe externalcircuit is connected phase shifting impedance which when conacross terminals 1 and .150, full scale deflec nected with the volt meter terminals and tlOnof thelinstrunientlcorresponds to 150 to a. olyphase circuit as hereinatter de- 31 1i? .fQl e il i iple and when the ex'ternal scrib yPermits the instrument to be used circuit is connec ed-a ss e inals land 7 for indicating the phase rotation of such 300,the resistance R isconnected in series circuit. with the coils-V and full s ale de e tion In carrying my invention intoeffect, I corresponds tO'3OO volt-s for example.

connect the higher voltage terminals of the The external reactance element i septavolt meter across two'phases of the circuit sented at 13 andis shown as actually'b'uilt 80 and note the volt meter deflect-ion. Then I in Fig. 2.. It consists'ot a laminated iron connect the reactance coil between another core 14 upon which is Wound a coil phase of the circuit and the lower voltage The laminations are secured in a suitable terminals of the volt meter. This causes -framework and support a terminal board 15 currents differing in'phase to flow through upon which are inounted'the binding posts 8 the volt meter coils and the resultant cur- 2 and3 and conductor bars 16 and 17, prefrent will be greater or less than before deerably spaced' and shaped to slip over the 40 pending upon whether the reactance current terminal posts 150 and 300 ot'the volt meter. vector is shifted toward or away from the The circuit connections are represented in original current vector of the volt meter Fig. 1 and'preferably include a switch 18 in no coils, or in other Words, the new Volt meter the circuit of the reactance coil X. The deflection will be larger or smaller dependreactance device may, it" desired/be built ing upon thedirection of phase rotation. into'the voltmeter case 10, butI prefer to The features of my invention which'l b'uild'it'as a separate instrument whichimay believe to be novel and patentable will be be easily attached to existing double scale pointed out in the claims appended hereto. volt'meters.

err-es v and X the external reactance coil.

Now let us assume that terminals 1 and 3 of Fig. 1 are connected across two phases of a three-phase circuit. This is the equiv alent of making the connection across terminals land 300 of the volt meter and the volt meter will indicate the voltage on the higher scale. Now, if we connect the remaining phase of the three-phase circuit to terminal 2 and close switch 18, we will have the arrangement schematically illustrated in Fig. 3 where V' represents the resistance of the volt meter coil, R the internal resistance element of the volt meter The volt meter coils are made to have a high resistance and low reactance in accordance with good practice in order that the volt meter will be substantially independent of frequency changes. WVhen the switch 18 is closed, the volt meter deflection will in- 7 crease or decrease, depending upon whether the phase rotation is 123 or 132, corresponding to clockwise and counterclockwise phase rotations respectively.

The reason for' this will be clear from a consideration of the vector diagrams shown inFigs. 4 and 5. In Fig. 4, 'il) represents the current vector for the volt meter coils alone, 2' 2", the corresponding vector for the resistance R, and 221:, the current vector for the reactance coil alone. In this case, a clockwise rotation is assumed and the vector z'm, instead of being drawn 120 degrees away from vectors iv and 2'1, lags nearly 90 degrees behind such position due to the well known lagging effect which the reactance X produces on the current flowing therethrough. The resultant current flowing through the volt meter coils V and the resistance B when the reactance coil is disconnected may be represented by the vector IM- obtained by adding vectors in and the reverse of i7 and corresponds to the voltmeter deflection under this condition. When the reactance coil X is connected as represented in F ig'. 3, the current flowing through the volt meter coils will have another comonent, namely, the resultant of the current owing through V and X, whi'chis obtained by adding vectors 2'00 and the reverse of it or Ioaz and the resultant current flowing through the volt meter coils will now be the vector sum of It? and 14100, or IV, corresponding to the new volt meter deflection which is appreciably greater than the original deflection corresponding to 1m. 7

In Fig. 5 the corresponding vector relations for a counterclockwise rotation are shown and are designated as in Fig. 4. Here vectors 17v and irhave the same positions as in Fig. 4, but ia: now lags behind in the opposite sense of rotation as compared to Fig. 4. The volt meter current I v'r, without the reactance X connected, is of the same magnitude as was the case in Fig. 4 and the volt meter deflection is the same, but withthe reactance coil X connected in, the volt meter deflection is decreased to the value corresponding to the resultant vector IV.

The invention is not limited to the case of a three-phase circuit, but is applicable to any polyphase circuit ,where the reactance connection to a third phase, as above de scribed, causes the resultant volt meter current to be different for diiferent directions of phase rotation. v

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown and described is only illustrative and that the invention maybe carried out by other means.

WVhat I claim as new and desire to secure by Letters Patent of the United States is 1. A combined voltmeterand phase rotation indicator comprising a voltmeter provided With a resistance, said voltmeterand resistance being connected in series across two phases of a polyphase circuit to indicate the voltage thereof, and a reactance arranged to be connected between another phase of the polyphase circuit and the voltmeter circuit at a point between said resistance and voltmeter to increase or decrease the current flowing through the voltmeter depending upon the direction of phase rotation.

2. In combination, an alternating current voltmeter of the dynamometer type, a resist-v ance connected in series with said voltmeter for voltage measurements and a phase moditying impedance arranged to be connected in star with said voltmeter and resistance for indicating phase rotation.

3. In combination, a polyphase circuit, a voltmeter, a resistance connected in series with said voltmeter across two phases of said circuit for indicating the voltage there of and a reactance arranged to be connected in star with said voltmeter and resistance to another phase of the circuit for indicating the phase rotation of said circuit.

4. Themethod of determining'the phase rotation of a polyphase circuit which consists in connecting the common and high voltage terminal of a double range voltmeter across two lines of the circuit and observing the voltmeter deflection and then connecting a reactance between the low voltage voltmeter terminal and another phase of the circuit and noting the change in deflection.

5. In combination, a double range voltmeter and a device for use therewith for determining phase rotation, comprising a on said board connected to one of said bars and a binding post connected in series With said coil to'the other bar. I

6. The method of determining the phase rotation of a polyphase circuit Which Con-- sists in connecting the common and high voltage terminal of a double range voltmeter across two phases of a polyphase circuit and my hand this 23rd day of May, 1924.

HORTON W. HALL. 

